Vehicular wireless networks (VWNs) offer both high-priority safety and low-priority non-safety applications. In VWNs, the high-priority applications are urgent. Transmitting urgent information demands low delay and high bandwidth. When the traffic is heavy, how to reduce the multi-hop wireless delay will be critical for urgent information. In this paper, we propose a blocking strategy to preempt the transmission of low-priority vehicles and to decrease the number of contending vehicles. Thus, the multi-hop wireless delay of high-priority vehicles will be greatly reduced even if the traffic is heavy. Moreover, we also propose a mathematical model to evaluate the performance of the proposed strategy and compare the existing strategy. Performance results show that the proposed strategy can reduce the multi-hop wireless delay significantly.